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mdns.c
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/*
* SPDX-FileCopyrightText: 2015-2025 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "freertos/semphr.h"
#include "esp_log.h"
#include "esp_event.h"
#include "esp_random.h"
#include "esp_check.h"
#include "mdns.h"
#include "mdns_private.h"
#include "mdns_networking.h"
static void _mdns_browse_item_free(mdns_browse_t *browse);
static esp_err_t _mdns_send_browse_action(mdns_action_type_t type, mdns_browse_t *browse);
static esp_err_t _mdns_sync_browse_action(mdns_action_type_t type, mdns_browse_sync_t *browse_sync);
static void _mdns_browse_sync(mdns_browse_sync_t *browse_sync);
static void _mdns_browse_finish(mdns_browse_t *browse);
static void _mdns_browse_add(mdns_browse_t *browse);
static void _mdns_browse_send(mdns_browse_t *browse, mdns_if_t interface);
#if CONFIG_ETH_ENABLED && CONFIG_MDNS_PREDEF_NETIF_ETH
#include "esp_eth.h"
#endif
#if ESP_IDF_VERSION <= ESP_IDF_VERSION_VAL(5, 1, 0)
#define MDNS_ESP_WIFI_ENABLED CONFIG_SOC_WIFI_SUPPORTED
#else
#define MDNS_ESP_WIFI_ENABLED CONFIG_ESP_WIFI_ENABLED
#endif
#if MDNS_ESP_WIFI_ENABLED && (CONFIG_MDNS_PREDEF_NETIF_STA || CONFIG_MDNS_PREDEF_NETIF_AP)
#include "esp_wifi.h"
#endif
#ifdef MDNS_ENABLE_DEBUG
void mdns_debug_packet(const uint8_t *data, size_t len);
#endif
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(array) (sizeof(array) / sizeof((array)[0]))
#endif
// Internal size of IPv6 address is defined here as size of AAAA record in mdns packet
// since the ip6_addr_t is defined in lwip and depends on using IPv6 zones
#define _MDNS_SIZEOF_IP6_ADDR (MDNS_ANSWER_AAAA_SIZE)
static const char *MDNS_DEFAULT_DOMAIN = "local";
static const char *MDNS_SUB_STR = "_sub";
mdns_server_t *_mdns_server = NULL;
static mdns_host_item_t *_mdns_host_list = NULL;
static mdns_host_item_t _mdns_self_host;
static const char *TAG = "mdns";
static volatile TaskHandle_t _mdns_service_task_handle = NULL;
static SemaphoreHandle_t _mdns_service_semaphore = NULL;
static void _mdns_search_finish_done(void);
static mdns_search_once_t *_mdns_search_find_from(mdns_search_once_t *search, mdns_name_t *name, uint16_t type, mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol);
static mdns_browse_t *_mdns_browse_find_from(mdns_browse_t *b, mdns_name_t *name, uint16_t type, mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol);
static void _mdns_browse_result_add_srv(mdns_browse_t *browse, const char *hostname, const char *instance, const char *service, const char *proto,
uint16_t port, mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol, uint32_t ttl, mdns_browse_sync_t *out_sync_browse);
static void _mdns_browse_result_add_ip(mdns_browse_t *browse, const char *hostname, esp_ip_addr_t *ip,
mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol, uint32_t ttl, mdns_browse_sync_t *out_sync_browse);
static void _mdns_browse_result_add_txt(mdns_browse_t *browse, const char *instance, const char *service, const char *proto,
mdns_txt_item_t *txt, uint8_t *txt_value_len, size_t txt_count, mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol,
uint32_t ttl, mdns_browse_sync_t *out_sync_browse);
#ifdef MDNS_ENABLE_DEBUG
static void debug_printf_browse_result(mdns_result_t *r_t, mdns_browse_t *b_t);
static void debug_printf_browse_result_all(mdns_result_t *r_t);
#endif // MDNS_ENABLE_DEBUG
static void _mdns_search_result_add_ip(mdns_search_once_t *search, const char *hostname, esp_ip_addr_t *ip,
mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol, uint32_t ttl);
static void _mdns_search_result_add_srv(mdns_search_once_t *search, const char *hostname, uint16_t port,
mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol, uint32_t ttl);
static void _mdns_search_result_add_txt(mdns_search_once_t *search, mdns_txt_item_t *txt, uint8_t *txt_value_len,
size_t txt_count, mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol,
uint32_t ttl);
static mdns_result_t *_mdns_search_result_add_ptr(mdns_search_once_t *search, const char *instance,
const char *service_type, const char *proto, mdns_if_t tcpip_if,
mdns_ip_protocol_t ip_protocol, uint32_t ttl);
static bool _mdns_append_host_list_in_services(mdns_out_answer_t **destination, mdns_srv_item_t *services[], size_t services_len, bool flush, bool bye);
static bool _mdns_append_host_list(mdns_out_answer_t **destination, bool flush, bool bye);
static void _mdns_remap_self_service_hostname(const char *old_hostname, const char *new_hostname);
static esp_err_t mdns_post_custom_action_tcpip_if(mdns_if_t mdns_if, mdns_event_actions_t event_action);
static void _mdns_query_results_free(mdns_result_t *results);
typedef enum {
MDNS_IF_STA = 0,
MDNS_IF_AP = 1,
MDNS_IF_ETH = 2,
} mdns_predef_if_t;
typedef struct mdns_interfaces mdns_interfaces_t;
struct mdns_interfaces {
const bool predefined;
esp_netif_t *netif;
const mdns_predef_if_t predef_if;
mdns_if_t duplicate;
};
/*
* @brief Internal collection of mdns supported interfaces
*
*/
static mdns_interfaces_t s_esp_netifs[MDNS_MAX_INTERFACES] = {
#if CONFIG_MDNS_PREDEF_NETIF_STA
{ .predefined = true, .netif = NULL, .predef_if = MDNS_IF_STA, .duplicate = MDNS_MAX_INTERFACES },
#endif
#if CONFIG_MDNS_PREDEF_NETIF_AP
{ .predefined = true, .netif = NULL, .predef_if = MDNS_IF_AP, .duplicate = MDNS_MAX_INTERFACES },
#endif
#if CONFIG_MDNS_PREDEF_NETIF_ETH
{ .predefined = true, .netif = NULL, .predef_if = MDNS_IF_ETH, .duplicate = MDNS_MAX_INTERFACES },
#endif
};
/**
* @brief Convert Predefined interface to the netif id from the internal netif list
* @param predef_if Predefined interface enum
* @return Ordinal number of internal list of mdns network interface.
* Returns MDNS_MAX_INTERFACES if the predefined interface wasn't found in the list
*/
static mdns_if_t mdns_if_from_preset_if(mdns_predef_if_t predef_if)
{
for (int i = 0; i < MDNS_MAX_INTERFACES; ++i) {
if (s_esp_netifs[i].predefined && s_esp_netifs[i].predef_if == predef_if) {
return i;
}
}
return MDNS_MAX_INTERFACES;
}
/**
* @brief Convert Predefined interface to esp-netif handle
* @param predef_if Predefined interface enum
* @return esp_netif pointer from system list of network interfaces
*/
static inline esp_netif_t *esp_netif_from_preset_if(mdns_predef_if_t predef_if)
{
switch (predef_if) {
case MDNS_IF_STA:
return esp_netif_get_handle_from_ifkey("WIFI_STA_DEF");
case MDNS_IF_AP:
return esp_netif_get_handle_from_ifkey("WIFI_AP_DEF");
#if CONFIG_ETH_ENABLED && CONFIG_MDNS_PREDEF_NETIF_ETH
case MDNS_IF_ETH:
return esp_netif_get_handle_from_ifkey("ETH_DEF");
#endif
default:
return NULL;
}
}
/**
* @brief Gets the actual esp_netif pointer from the internal network interface list
*
* The supplied ordinal number could
* - point to a predef netif -> "STA", "AP", "ETH"
* - if no entry in the list (NULL) -> check if the system added this netif
* - point to a custom netif -> just return the entry in the list
* - users is responsible for the lifetime of this netif (to be valid between mdns-init -> deinit)
*
* @param tcpip_if Ordinal number of the interface
* @return Pointer ot the esp_netif object if the interface is available, NULL otherwise
*/
esp_netif_t *_mdns_get_esp_netif(mdns_if_t tcpip_if)
{
if (tcpip_if < MDNS_MAX_INTERFACES) {
if (s_esp_netifs[tcpip_if].netif == NULL && s_esp_netifs[tcpip_if].predefined) {
// If the local copy is NULL and this netif is predefined -> we can find it in the global netif list
s_esp_netifs[tcpip_if].netif = esp_netif_from_preset_if(s_esp_netifs[tcpip_if].predef_if);
// failing to find it means that the netif is *not* available -> return NULL
}
return s_esp_netifs[tcpip_if].netif;
}
return NULL;
}
/*
* @brief Clean internal mdns interface's pointer
*/
static inline void _mdns_clean_netif_ptr(mdns_if_t tcpip_if)
{
if (tcpip_if < MDNS_MAX_INTERFACES) {
s_esp_netifs[tcpip_if].netif = NULL;
}
}
/*
* @brief Convert esp-netif handle to mdns if
*/
static mdns_if_t _mdns_get_if_from_esp_netif(esp_netif_t *esp_netif)
{
for (int i = 0; i < MDNS_MAX_INTERFACES; ++i) {
// The predefined netifs in the static array are NULL when firstly calling this function
// if IPv4 is disabled. Set these netifs here.
if (s_esp_netifs[i].netif == NULL && s_esp_netifs[i].predefined) {
s_esp_netifs[i].netif = esp_netif_from_preset_if(s_esp_netifs[i].predef_if);
}
if (esp_netif == s_esp_netifs[i].netif) {
return i;
}
}
return MDNS_MAX_INTERFACES;
}
static inline bool _str_null_or_empty(const char *str)
{
return (str == NULL || *str == 0);
}
/*
* @brief Appends/increments a number to name/instance in case of collision
* */
static char *_mdns_mangle_name(char *in)
{
char *p = strrchr(in, '-');
int suffix = 0;
if (p == NULL) {
//No - in ``in``
suffix = 2;
} else {
char *endp = NULL;
suffix = strtol(p + 1, &endp, 10);
if (*endp != 0) {
//suffix is not numerical
suffix = 2;
p = NULL; //so we append -suffix to the entire string
}
}
char *ret;
if (p == NULL) {
//need to add -2 to string
ret = malloc(strlen(in) + 3);
if (ret == NULL) {
HOOK_MALLOC_FAILED;
return NULL;
}
sprintf(ret, "%s-2", in);
} else {
size_t in_len = strlen(in);
ret = malloc(in_len + 2); //one extra byte in case 9-10 or 99-100 etc
if (ret == NULL) {
HOOK_MALLOC_FAILED;
return NULL;
}
memcpy(ret, in, in_len);
int baseLen = p - in; //length of 'bla' in 'bla-123'
//overwrite suffix with new suffix
sprintf(ret + baseLen, "-%d", suffix + 1);
}
return ret;
}
static bool _mdns_service_match(const mdns_service_t *srv, const char *service, const char *proto,
const char *hostname)
{
if (!service || !proto || !srv->hostname) {
return false;
}
return !strcasecmp(srv->service, service) && !strcasecmp(srv->proto, proto) &&
(_str_null_or_empty(hostname) || !strcasecmp(srv->hostname, hostname));
}
/**
* @brief finds service from given service type
* @param server the server
* @param service service type to match
* @param proto proto to match
* @param hostname hostname of the service (if non-null)
*
* @return the service item if found or NULL on error
*/
static mdns_srv_item_t *_mdns_get_service_item(const char *service, const char *proto, const char *hostname)
{
mdns_srv_item_t *s = _mdns_server->services;
while (s) {
if (_mdns_service_match(s->service, service, proto, hostname)) {
return s;
}
s = s->next;
}
return NULL;
}
static mdns_srv_item_t *_mdns_get_service_item_subtype(const char *subtype, const char *service, const char *proto)
{
mdns_srv_item_t *s = _mdns_server->services;
while (s) {
if (_mdns_service_match(s->service, service, proto, NULL)) {
mdns_subtype_t *subtype_item = s->service->subtype;
while (subtype_item) {
if (!strcasecmp(subtype_item->subtype, subtype)) {
return s;
}
subtype_item = subtype_item->next;
}
}
s = s->next;
}
return NULL;
}
static mdns_host_item_t *mdns_get_host_item(const char *hostname)
{
if (hostname == NULL || strcasecmp(hostname, _mdns_server->hostname) == 0) {
return &_mdns_self_host;
}
mdns_host_item_t *host = _mdns_host_list;
while (host != NULL) {
if (strcasecmp(host->hostname, hostname) == 0) {
return host;
}
host = host->next;
}
return NULL;
}
static bool _mdns_can_add_more_services(void)
{
#if MDNS_MAX_SERVICES == 0
return false;
#else
mdns_srv_item_t *s = _mdns_server->services;
uint16_t service_num = 0;
while (s) {
service_num ++;
s = s->next;
if (service_num >= MDNS_MAX_SERVICES) {
return false;
}
}
return true;
#endif
}
esp_err_t _mdns_send_rx_action(mdns_rx_packet_t *packet)
{
mdns_action_t *action = NULL;
action = (mdns_action_t *)malloc(sizeof(mdns_action_t));
if (!action) {
HOOK_MALLOC_FAILED;
return ESP_ERR_NO_MEM;
}
action->type = ACTION_RX_HANDLE;
action->data.rx_handle.packet = packet;
if (xQueueSend(_mdns_server->action_queue, &action, (TickType_t)0) != pdPASS) {
free(action);
return ESP_ERR_NO_MEM;
}
return ESP_OK;
}
static const char *_mdns_get_default_instance_name(void)
{
if (_mdns_server && !_str_null_or_empty(_mdns_server->instance)) {
return _mdns_server->instance;
}
if (_mdns_server && !_str_null_or_empty(_mdns_server->hostname)) {
return _mdns_server->hostname;
}
return NULL;
}
/**
* @brief Get the service name of a service
*/
static const char *_mdns_get_service_instance_name(const mdns_service_t *service)
{
if (service && !_str_null_or_empty(service->instance)) {
return service->instance;
}
return _mdns_get_default_instance_name();
}
static bool _mdns_instance_name_match(const char *lhs, const char *rhs)
{
if (lhs == NULL) {
lhs = _mdns_get_default_instance_name();
}
if (rhs == NULL) {
rhs = _mdns_get_default_instance_name();
}
return !strcasecmp(lhs, rhs);
}
static bool _mdns_service_match_instance(const mdns_service_t *srv, const char *instance, const char *service,
const char *proto, const char *hostname)
{
// service and proto must be supplied, if not this instance won't match
if (!service || !proto) {
return false;
}
// instance==NULL -> _mdns_instance_name_match() will check the default instance
// hostname==NULL -> matches if instance, service and proto matches
return !strcasecmp(srv->service, service) && _mdns_instance_name_match(srv->instance, instance) &&
!strcasecmp(srv->proto, proto) && (_str_null_or_empty(hostname) || !strcasecmp(srv->hostname, hostname));
}
static mdns_srv_item_t *_mdns_get_service_item_instance(const char *instance, const char *service, const char *proto,
const char *hostname)
{
mdns_srv_item_t *s = _mdns_server->services;
while (s) {
if (instance) {
if (_mdns_service_match_instance(s->service, instance, service, proto, hostname)) {
return s;
}
} else {
if (_mdns_service_match(s->service, service, proto, hostname)) {
return s;
}
}
s = s->next;
}
return NULL;
}
/**
* @brief reads MDNS FQDN into mdns_name_t structure
* FQDN is in format: [hostname.|[instance.]_service._proto.]local.
*
* @param packet MDNS packet
* @param start Starting point of FQDN
* @param name mdns_name_t structure to populate
* @param buf temporary char buffer
*
* @return the address after the parsed FQDN in the packet or NULL on error
*/
static const uint8_t *_mdns_read_fqdn(const uint8_t *packet, const uint8_t *start, mdns_name_t *name, char *buf, size_t packet_len)
{
size_t index = 0;
const uint8_t *packet_end = packet + packet_len;
while (start + index < packet_end && start[index]) {
if (name->parts == 4) {
name->invalid = true;
}
uint8_t len = start[index++];
if (len < 0xC0) {
if (len > 63) {
//length can not be more than 63
return NULL;
}
uint8_t i;
for (i = 0; i < len; i++) {
if (start + index >= packet_end) {
return NULL;
}
buf[i] = start[index++];
}
buf[len] = '\0';
if (name->parts == 1 && buf[0] != '_'
&& (strcasecmp(buf, MDNS_DEFAULT_DOMAIN) != 0)
&& (strcasecmp(buf, "arpa") != 0)
#ifndef CONFIG_MDNS_RESPOND_REVERSE_QUERIES
&& (strcasecmp(buf, "ip6") != 0)
&& (strcasecmp(buf, "in-addr") != 0)
#endif
) {
strlcat(name->host, ".", sizeof(name->host));
strlcat(name->host, buf, sizeof(name->host));
} else if (strcasecmp(buf, MDNS_SUB_STR) == 0) {
name->sub = 1;
} else if (!name->invalid) {
char *mdns_name_ptrs[] = {name->host, name->service, name->proto, name->domain};
memcpy(mdns_name_ptrs[name->parts++], buf, len + 1);
}
} else {
size_t address = (((uint16_t)len & 0x3F) << 8) | start[index++];
if ((packet + address) >= start) {
//reference address can not be after where we are
return NULL;
}
if (_mdns_read_fqdn(packet, packet + address, name, buf, packet_len)) {
return start + index;
}
return NULL;
}
}
return start + index + 1;
}
/**
* @brief sets uint16_t value in a packet
*
* @param packet MDNS packet
* @param index offset of uint16_t value
* @param value the value to set
*/
static inline void _mdns_set_u16(uint8_t *packet, uint16_t index, uint16_t value)
{
if ((index + 1) >= MDNS_MAX_PACKET_SIZE) {
return;
}
packet[index] = (value >> 8) & 0xFF;
packet[index + 1] = value & 0xFF;
}
/**
* @brief appends byte in a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param value the value to set
*
* @return length of added data: 0 on error or 1 on success
*/
static inline uint8_t _mdns_append_u8(uint8_t *packet, uint16_t *index, uint8_t value)
{
if (*index >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
packet[*index] = value;
*index += 1;
return 1;
}
/**
* @brief appends uint16_t in a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param value the value to set
*
* @return length of added data: 0 on error or 2 on success
*/
static inline uint8_t _mdns_append_u16(uint8_t *packet, uint16_t *index, uint16_t value)
{
if ((*index + 1) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
_mdns_append_u8(packet, index, (value >> 8) & 0xFF);
_mdns_append_u8(packet, index, value & 0xFF);
return 2;
}
/**
* @brief appends uint32_t in a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param value the value to set
*
* @return length of added data: 0 on error or 4 on success
*/
static inline uint8_t _mdns_append_u32(uint8_t *packet, uint16_t *index, uint32_t value)
{
if ((*index + 3) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
_mdns_append_u8(packet, index, (value >> 24) & 0xFF);
_mdns_append_u8(packet, index, (value >> 16) & 0xFF);
_mdns_append_u8(packet, index, (value >> 8) & 0xFF);
_mdns_append_u8(packet, index, value & 0xFF);
return 4;
}
/**
* @brief appends answer type, class, ttl and data length to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param type answer type
* @param ttl answer ttl
*
* @return length of added data: 0 on error or 10 on success
*/
static inline uint8_t _mdns_append_type(uint8_t *packet, uint16_t *index, uint8_t type, bool flush, uint32_t ttl)
{
if ((*index + 10) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
uint16_t mdns_class = MDNS_CLASS_IN;
if (flush) {
mdns_class = MDNS_CLASS_IN_FLUSH_CACHE;
}
if (type == MDNS_ANSWER_PTR) {
_mdns_append_u16(packet, index, MDNS_TYPE_PTR);
_mdns_append_u16(packet, index, mdns_class);
} else if (type == MDNS_ANSWER_TXT) {
_mdns_append_u16(packet, index, MDNS_TYPE_TXT);
_mdns_append_u16(packet, index, mdns_class);
} else if (type == MDNS_ANSWER_SRV) {
_mdns_append_u16(packet, index, MDNS_TYPE_SRV);
_mdns_append_u16(packet, index, mdns_class);
} else if (type == MDNS_ANSWER_A) {
_mdns_append_u16(packet, index, MDNS_TYPE_A);
_mdns_append_u16(packet, index, mdns_class);
} else if (type == MDNS_ANSWER_AAAA) {
_mdns_append_u16(packet, index, MDNS_TYPE_AAAA);
_mdns_append_u16(packet, index, mdns_class);
} else {
return 0;
}
_mdns_append_u32(packet, index, ttl);
_mdns_append_u16(packet, index, 0);
return 10;
}
static inline uint8_t _mdns_append_string_with_len(uint8_t *packet, uint16_t *index, const char *string, uint8_t len)
{
if ((*index + len + 1) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
_mdns_append_u8(packet, index, len);
memcpy(packet + *index, string, len);
*index += len;
return len + 1;
}
/**
* @brief appends single string to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param string the string to append
*
* @return length of added data: 0 on error or length of the string + 1 on success
*/
static inline uint8_t _mdns_append_string(uint8_t *packet, uint16_t *index, const char *string)
{
uint8_t len = strlen(string);
if ((*index + len + 1) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
_mdns_append_u8(packet, index, len);
memcpy(packet + *index, string, len);
*index += len;
return len + 1;
}
/**
* @brief appends one TXT record ("key=value" or "key")
*
* @param packet MDNS packet
* @param index offset in the packet
* @param txt one txt record
*
* @return length of added data: length of the added txt value + 1 on success
* 0 if data won't fit the packet
* -1 if invalid TXT entry
*/
static inline int append_one_txt_record_entry(uint8_t *packet, uint16_t *index, mdns_txt_linked_item_t *txt)
{
if (txt == NULL || txt->key == NULL) {
return -1;
}
size_t key_len = strlen(txt->key);
size_t len = key_len + txt->value_len + (txt->value ? 1 : 0);
if ((*index + len + 1) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
_mdns_append_u8(packet, index, len);
memcpy(packet + *index, txt->key, key_len);
if (txt->value) {
packet[*index + key_len] = '=';
memcpy(packet + *index + key_len + 1, txt->value, txt->value_len);
}
*index += len;
return len + 1;
}
#ifdef CONFIG_MDNS_RESPOND_REVERSE_QUERIES
static inline int append_single_str(uint8_t *packet, uint16_t *index, const char *str, int len)
{
if ((*index + len + 1) >= MDNS_MAX_PACKET_SIZE) {
return 0;
}
if (!_mdns_append_u8(packet, index, len)) {
return 0;
}
memcpy(packet + *index, str, len);
*index += len;
return *index;
}
/**
* @brief appends FQDN to a packet from hostname separated by dots. This API works the same way as
* _mdns_append_fqdn(), but refrains from DNS compression (as it's mainly used for IP addresses (many short items),
* where we gain very little (or compression even gets counter-productive mainly for IPv6 addresses)
*
* @param packet MDNS packet
* @param index offset in the packet
* @param name name representing FQDN in '.' separated parts
* @param last true if appending the last part (domain, typically "arpa")
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t append_fqdn_dots(uint8_t *packet, uint16_t *index, const char *name, bool last)
{
int len = strlen(name);
char *host = (char *)name;
char *end = host;
char *start = host;
do {
end = memchr(start, '.', host + len - start);
end = end ? end : host + len;
int part_len = end - start;
if (!append_single_str(packet, index, start, part_len)) {
return 0;
}
start = ++end;
} while (end < name + len);
if (!append_single_str(packet, index, "arpa", sizeof("arpa") - 1)) {
return 0;
}
//empty string so terminate
if (!_mdns_append_u8(packet, index, 0)) {
return 0;
}
return *index;
}
#endif /* CONFIG_MDNS_RESPOND_REVERSE_QUERIES */
/**
* @brief appends FQDN to a packet, incrementing the index and
* compressing the output if previous occurrence of the string (or part of it) has been found
*
* @param packet MDNS packet
* @param index offset in the packet
* @param strings string array containing the parts of the FQDN
* @param count number of strings in the array
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_fqdn(uint8_t *packet, uint16_t *index, const char *strings[], uint8_t count, size_t packet_len)
{
if (!count) {
//empty string so terminate
return _mdns_append_u8(packet, index, 0);
}
static char buf[MDNS_NAME_BUF_LEN];
uint8_t len = strlen(strings[0]);
//try to find first the string length in the packet (if it exists)
uint8_t *len_location = (uint8_t *)memchr(packet, (char)len, *index);
while (len_location) {
mdns_name_t name;
//check if the string after len_location is the string that we are looking for
if (memcmp(len_location + 1, strings[0], len)) { //not continuing with our string
search_next:
//try and find the length byte further in the packet
len_location = (uint8_t *)memchr(len_location + 1, (char)len, *index - (len_location + 1 - packet));
continue;
}
//seems that we might have found the string that we are looking for
//read the destination into name and compare
name.parts = 0;
name.sub = 0;
name.invalid = false;
name.host[0] = 0;
name.service[0] = 0;
name.proto[0] = 0;
name.domain[0] = 0;
const uint8_t *content = _mdns_read_fqdn(packet, len_location, &name, buf, packet_len);
if (!content) {
//not a readable fqdn?
goto search_next; // could be our unfinished fqdn, continue searching
}
if (name.parts == count) {
uint8_t i;
for (i = 0; i < count; i++) {
if (strcasecmp(strings[i], (const char *)&name + (i * (MDNS_NAME_BUF_LEN)))) {
//not our string! let's search more
goto search_next;
}
}
//we actually have found the string
break;
} else {
goto search_next;
}
}
//string is not yet in the packet, so let's add it
if (!len_location) {
uint8_t written = _mdns_append_string(packet, index, strings[0]);
if (!written) {
return 0;
}
//run the same for the other strings in the name
return written + _mdns_append_fqdn(packet, index, &strings[1], count - 1, packet_len);
}
//we have found the string so let's insert a pointer to it instead
uint16_t offset = len_location - packet;
offset |= MDNS_NAME_REF;
return _mdns_append_u16(packet, index, offset);
}
/**
* @brief appends PTR record for service to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param server the server that is hosting the service
* @param service the service to add record for
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_ptr_record(uint8_t *packet, uint16_t *index, const char *instance, const char *service, const char *proto, bool flush, bool bye)
{
const char *str[4];
uint16_t record_length = 0;
uint8_t part_length;
if (service == NULL) {
return 0;
}
str[0] = instance;
str[1] = service;
str[2] = proto;
str[3] = MDNS_DEFAULT_DOMAIN;
part_length = _mdns_append_fqdn(packet, index, str + 1, 3, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
record_length += part_length;
part_length = _mdns_append_type(packet, index, MDNS_ANSWER_PTR, false, bye ? 0 : MDNS_ANSWER_PTR_TTL);
if (!part_length) {
return 0;
}
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
_mdns_set_u16(packet, data_len_location, part_length);
record_length += part_length;
return record_length;
}
/**
* @brief appends PTR record for a subtype to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param instance the service instance name
* @param subtype the service subtype
* @param proto the service protocol
* @param flush whether to set the flush flag
* @param bye whether to set the bye flag
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_subtype_ptr_record(uint8_t *packet, uint16_t *index, const char *instance,
const char *subtype, const char *service, const char *proto, bool flush,
bool bye)
{
const char *subtype_str[5] = {subtype, MDNS_SUB_STR, service, proto, MDNS_DEFAULT_DOMAIN};
const char *instance_str[4] = {instance, service, proto, MDNS_DEFAULT_DOMAIN};
uint16_t record_length = 0;
uint8_t part_length;
if (service == NULL) {
return 0;
}
part_length = _mdns_append_fqdn(packet, index, subtype_str, ARRAY_SIZE(subtype_str), MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
record_length += part_length;
part_length = _mdns_append_type(packet, index, MDNS_ANSWER_PTR, false, bye ? 0 : MDNS_ANSWER_PTR_TTL);
if (!part_length) {
return 0;
}
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, instance_str, ARRAY_SIZE(instance_str), MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
_mdns_set_u16(packet, data_len_location, part_length);
record_length += part_length;
return record_length;
}
/**
* @brief appends DNS-SD PTR record for service to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param server the server that is hosting the service
* @param service the service to add record for
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_sdptr_record(uint8_t *packet, uint16_t *index, mdns_service_t *service, bool flush, bool bye)
{
const char *str[3];
const char *sd_str[4];
uint16_t record_length = 0;
uint8_t part_length;
if (service == NULL) {
return 0;
}
sd_str[0] = (char *)"_services";
sd_str[1] = (char *)"_dns-sd";
sd_str[2] = (char *)"_udp";
sd_str[3] = MDNS_DEFAULT_DOMAIN;
str[0] = service->service;
str[1] = service->proto;
str[2] = MDNS_DEFAULT_DOMAIN;
part_length = _mdns_append_fqdn(packet, index, sd_str, 4, MDNS_MAX_PACKET_SIZE);
record_length += part_length;
part_length = _mdns_append_type(packet, index, MDNS_ANSWER_PTR, flush, MDNS_ANSWER_PTR_TTL);
if (!part_length) {
return 0;
}
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, str, 3, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
_mdns_set_u16(packet, data_len_location, part_length);
record_length += part_length;
return record_length;
}
/**
* @brief appends TXT record for service to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param server the server that is hosting the service
* @param service the service to add record for
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_txt_record(uint8_t *packet, uint16_t *index, mdns_service_t *service, bool flush, bool bye)
{
const char *str[4];
uint16_t record_length = 0;
uint8_t part_length;
if (service == NULL) {
return 0;
}
str[0] = _mdns_get_service_instance_name(service);
str[1] = service->service;
str[2] = service->proto;
str[3] = MDNS_DEFAULT_DOMAIN;
if (!str[0]) {
return 0;
}
part_length = _mdns_append_fqdn(packet, index, str, 4, MDNS_MAX_PACKET_SIZE);
if (!part_length) {
return 0;
}
record_length += part_length;
part_length = _mdns_append_type(packet, index, MDNS_ANSWER_TXT, flush, bye ? 0 : MDNS_ANSWER_TXT_TTL);
if (!part_length) {
return 0;
}
record_length += part_length;
uint16_t data_len_location = *index - 2;
uint16_t data_len = 0;
mdns_txt_linked_item_t *txt = service->txt;